Which of the following is not necessary for the greenhouse effect?

The sun

The atmosphere

The oceans

Carbon dioxide

The oceans is the answer

The 'greenhouse effect ' is an atmospheric heating phenomenon in which the Earth experiences rise in temperature because certain gases (water vapor, carbon dioxide, nitrous oxide, and methane) in the atmosphere allow incoming sunlight to pass through but trap heat radiated from the earth's surface. But Technically the answer is The Ocean